The present disclosure relates to a photo-detector such as a CAPD (Current Assisted Photonic Demodulator) detecting photo-electrons generated in a substrate by an incident light.
A photo-detector such as a CAPD may be used as a TOF (Time Of Flight) sensor. The TOF sensor irradiates light to a target and detects light reflected from the target. Particularly, the TOF sensor can measure a distance to the target using a phase difference between the irradiated light signal and the reflected light signal.
The photo-detector may includes a substrate having a light receiving region, a detection region for collecting minority carriers (e.g., electrons) generated in the light receiving region by an incident light, and field generating regions generating a majority carrier current used as a guide current for moving the electrons towards the detection region in the light receiving region. Different guide voltages may be applied to the field generating regions to generate the majority carrier current, and majority carriers (e.g., holes) generated in the light receiving region may become part of the majority carrier current and move towards the field generating region, to which a relatively low guide voltage is applied. The minority charge carriers may move or drift in the opposite direction (i.e., towards the field generating region), to which a relatively high guide voltage is applied, and then diffuse into the detection region. Then, the electrons may become part of an output photocurrent.